• If you’re self-publishing, no.
• If you want to approach mainstream publishing houses, then probably yes.

There’s nothing to stop you sending your book to as many publishers as you can think of, but the chances are that your precious manuscript will languish in a toppling slush pile to be read (if you’re lucky) by a bored intern. It is unlikely to reach the attention of anyone who commissions books unless it’s rescued from this pile and thought exceptional. This has been known (cf J K Rowling) but isn’t usual.

The agent is your intermediary. They know the business and will more than likely have worked at a high level in publishing. They have a well-established network of commissioning editors and publishers so they know who is most likely to buy your book.

A good agent will:

• Take you on if your work is potentially saleable to a publisher.
• Help you shape your book to make it more so.
• Check and advise on your proposal (pitch).
• Know which editors/houses to pitch your book to.
• Contact them directly on your behalf.
• Negotiate the best deal for you for e.g. the advance, royalties and rights.
• Advise on and suggest new ideas and support you ‘between books’.

For this they will take between 10% and 20% of everything you earn from the deals they negotiate for you.

Money well spent, I say.

My agent has sold four books for me so far; two ended up in modest auctions with three publishers bidding. But my chances of grabbing the attention of a single publisher without her would, I suspect, have been close to zero. I owe her a great deal more than the paltry percentages she’s earned from my work over the past decade.